A long‐term field experiment was conducted to determine the effect of the additions of urban waste compost on the physical and chemical properties and enzymatic activities in a calcareous soil (Fluventic Xerochrept). Total porosity (pores >50 µm measured on thin soil sections from undisturbed samples by image analysis) was greater in the plots treated with compost than the control plots due to a larger amount of elongated pores. In the amended plots total and humified organic C, Pb, Cu, and Zn showed a significant increase compared with nonamended plots. Enzymatic activities (L‐asparaginase, arylsulphatase, dehydrogenase, phosphodiesterase, and alkaline phosphomonoesterase) were significantly enhanced by the compost addition thus indicating no inhibiting influence of the heavy metals present. The increased levels of the arylsulphatase, dehydrogenase, phosphodiesterase, and phosphomonoesterase activities were significantly correlated with total porosity: the first three with pores ranging from 50 to 1000 µm, mainly with pores 50 to 200 µm in size, and phosphomonoesterase only with pores whose size was <500 µm. L‐asparaginase activity was not correlated with porosity. Only arylsulphatase, dehydrogenase, and phosphodiesterase were negatively correlated with bulk density.
Selenium
(Se) is an important micronutrient for living organisms,
since it is involved in several physiological and metabolic processes.
Se intake in humans is often low and very seldom excessive, and its
bioavailability depends also on its chemical form, with organic Se
as the most available after ingestion. The main dietary source of
Se for humans is represented by plants, since many species are able
to metabolize and accumulate organic Se in edible parts to be consumed
directly (leaves, flowers, fruits, seeds, and sprouts) or after processing
(oil, wine, etc.). Countless studies have recently investigated the
Se biofortification of plants to produce Se-enriched foods and elicit
the production of secondary metabolites, which may benefit human health
when incorporated into the diet. Moreover, feeding animals Se-rich
diets may provide Se-enriched meat. This work reviews the most recent
literature on the nutraceutical profile of Se-enriched foods from
plant and animal sources.
The contents of total Se and of inorganic and organic Se species, as well as the contents of proteins, chlorophylls, carotenoids, and phenolic acids, were measured in 10-day old sprouts of rice ( Oryza sativa L.) obtained with increasing levels (15, 45, 135, and 405 mg Se L) of sodium selenite and sodium selenate and with distilled water as control. Increasing Se levels increased organic and inorganic Se contents of sprouts, as well as the content of phenolic acids, especially in their soluble conjugated forms. Moderate levels of sodium selenite (i.e., not higher that 45 mg L) appeared the best compromise to obtain high Se and phenolic acid yields together with high proportion of organic Se while limiting residual Se in the germination substrate waste. Se biofortification of rice sprouts appears a feasible and efficient way to promote Se and phenolic acid intake in human diet, with well-known health benefits.
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